Baseline dental examinations were conducted in October 1972, on approximately 2200 first through twelfth grade children in Nelson County, Virginia. All study participants in grades 1-6 chew daily in school under supervision of the classroom teacher acidulated phosphate-fluoride (APF) tablet containing 1 mg. F, rinse for 30 seconds with the resulting solution and then swallow the material. Once a week in school the same children also swish 10 milliliters of a 0.2 percent sodium fluoride solution for 30 seconds and then empty the contents of the mouth into a cup. A fluoride-containing dentifrice is distributed to the same children for use at home, and they receive toothbrushes periodically to take home. These combined preventive procedures will continue in the elementary schools for a minimum of ten years. Follow-up dental examinations are carried out biennially in all schools. The first follow-up survey was done in October 1974. Data were presented at the 1976 meeting of the International Association for Dental Research.